PURPOSE: The purpose of this study was to investigate the results of arthroscopic treatment of acetabular labral tears (the most common indication for hip arthroscopy) in a consecutive series of patients with 10-year follow-up. METHODS: Since 1993, all of our patients undergoing hip arthroscopy have been prospectively assessed by use of a modified Harris Hip Score preoperatively and postoperatively at 3, 12, 24, 60, and 120 months. Variables recorded include age, sex, diagnosis, duration of symptoms, onset of symptoms, center-edge angle, Workers' compensation status, and pending litigation. From a cohort of 52 procedures performed on 50 patients who had achieved 10-year follow-up, 29 patients (31 hips) were treated for a tear of the acetabular labrum and represent the substance of this study. RESULTS: There was 100% follow-up, excluding 3 patients (5 hips) who died before their 10-year assessment. The mean age was 46 years (range, 17 to 84 years); there were 13 male and 13 female patients. The median Harris Hip Score improvement was 29 points (from 52 points preoperatively to 81 points postoperatively). Among 18 patients without arthritis, 15 (83%) continued to show substantial improvement (>or=18 points) at 10-year follow-up. Among 8 patients with associated arthritis, 7 (88%) were converted to total hip arthroplasty at a mean of 63 months. Two patients underwent repeat arthroscopy, which did not preclude a successful outcome at 10-year follow-up. There were no complications. CONCLUSIONS: Selective debridement of symptomatic tears can result in favorable long-term results. The presence of clinical findings of arthritis at the time of the index procedure is a poor prognostic indicator, with uniformly poor results at 10 years. LEVEL OF EVIDENCE: Level IV, therapeutic case series.